1 /*
2 * Copyright (C) 2001-2002 Sistina Software (UK) Limited.
3 * Copyright (C) 2006-2008 Red Hat GmbH
4 *
5 * This file is released under the GPL.
6 */
7
8 #include "dm-exception-store.h"
9
10 #include <linux/mm.h>
11 #include <linux/pagemap.h>
12 #include <linux/vmalloc.h>
13 #include <linux/export.h>
14 #include <linux/slab.h>
15 #include <linux/dm-io.h>
16
17 #define DM_MSG_PREFIX "transient snapshot"
18
19 /*-----------------------------------------------------------------
20 * Implementation of the store for non-persistent snapshots.
21 *---------------------------------------------------------------*/
22 struct transient_c {
23 sector_t next_free;
24 };
25
transient_dtr(struct dm_exception_store * store)26 static void transient_dtr(struct dm_exception_store *store)
27 {
28 kfree(store->context);
29 }
30
transient_read_metadata(struct dm_exception_store * store,int (* callback)(void * callback_context,chunk_t old,chunk_t new),void * callback_context)31 static int transient_read_metadata(struct dm_exception_store *store,
32 int (*callback)(void *callback_context,
33 chunk_t old, chunk_t new),
34 void *callback_context)
35 {
36 return 0;
37 }
38
transient_prepare_exception(struct dm_exception_store * store,struct dm_exception * e)39 static int transient_prepare_exception(struct dm_exception_store *store,
40 struct dm_exception *e)
41 {
42 struct transient_c *tc = store->context;
43 sector_t size = get_dev_size(dm_snap_cow(store->snap)->bdev);
44
45 if (size < (tc->next_free + store->chunk_size))
46 return -1;
47
48 e->new_chunk = sector_to_chunk(store, tc->next_free);
49 tc->next_free += store->chunk_size;
50
51 return 0;
52 }
53
transient_commit_exception(struct dm_exception_store * store,struct dm_exception * e,int valid,void (* callback)(void *,int success),void * callback_context)54 static void transient_commit_exception(struct dm_exception_store *store,
55 struct dm_exception *e, int valid,
56 void (*callback) (void *, int success),
57 void *callback_context)
58 {
59 /* Just succeed */
60 callback(callback_context, valid);
61 }
62
transient_usage(struct dm_exception_store * store,sector_t * total_sectors,sector_t * sectors_allocated,sector_t * metadata_sectors)63 static void transient_usage(struct dm_exception_store *store,
64 sector_t *total_sectors,
65 sector_t *sectors_allocated,
66 sector_t *metadata_sectors)
67 {
68 *sectors_allocated = ((struct transient_c *) store->context)->next_free;
69 *total_sectors = get_dev_size(dm_snap_cow(store->snap)->bdev);
70 *metadata_sectors = 0;
71 }
72
transient_ctr(struct dm_exception_store * store,char * options)73 static int transient_ctr(struct dm_exception_store *store, char *options)
74 {
75 struct transient_c *tc;
76
77 tc = kmalloc(sizeof(struct transient_c), GFP_KERNEL);
78 if (!tc)
79 return -ENOMEM;
80
81 tc->next_free = 0;
82 store->context = tc;
83
84 return 0;
85 }
86
transient_status(struct dm_exception_store * store,status_type_t status,char * result,unsigned maxlen)87 static unsigned transient_status(struct dm_exception_store *store,
88 status_type_t status, char *result,
89 unsigned maxlen)
90 {
91 unsigned sz = 0;
92
93 switch (status) {
94 case STATUSTYPE_INFO:
95 break;
96 case STATUSTYPE_TABLE:
97 DMEMIT(" N %llu", (unsigned long long)store->chunk_size);
98 break;
99 case STATUSTYPE_IMA:
100 *result = '\0';
101 break;
102 }
103
104 return sz;
105 }
106
107 static struct dm_exception_store_type _transient_type = {
108 .name = "transient",
109 .module = THIS_MODULE,
110 .ctr = transient_ctr,
111 .dtr = transient_dtr,
112 .read_metadata = transient_read_metadata,
113 .prepare_exception = transient_prepare_exception,
114 .commit_exception = transient_commit_exception,
115 .usage = transient_usage,
116 .status = transient_status,
117 };
118
119 static struct dm_exception_store_type _transient_compat_type = {
120 .name = "N",
121 .module = THIS_MODULE,
122 .ctr = transient_ctr,
123 .dtr = transient_dtr,
124 .read_metadata = transient_read_metadata,
125 .prepare_exception = transient_prepare_exception,
126 .commit_exception = transient_commit_exception,
127 .usage = transient_usage,
128 .status = transient_status,
129 };
130
dm_transient_snapshot_init(void)131 int dm_transient_snapshot_init(void)
132 {
133 int r;
134
135 r = dm_exception_store_type_register(&_transient_type);
136 if (r) {
137 DMWARN("Unable to register transient exception store type");
138 return r;
139 }
140
141 r = dm_exception_store_type_register(&_transient_compat_type);
142 if (r) {
143 DMWARN("Unable to register old-style transient "
144 "exception store type");
145 dm_exception_store_type_unregister(&_transient_type);
146 return r;
147 }
148
149 return r;
150 }
151
dm_transient_snapshot_exit(void)152 void dm_transient_snapshot_exit(void)
153 {
154 dm_exception_store_type_unregister(&_transient_type);
155 dm_exception_store_type_unregister(&_transient_compat_type);
156 }
157